How TVA Manages Water Levels

Taming the Tennessee River was TVA’s first task, and it got the job done by building a system of dams and reservoirs to control flooding and generate power. Today, TVA also manages the river flow to meet many other needs, including protecting water quality, ensuring year-round navigation and providing water supply for power production as well as municipal, agricultural and industrial use. During the summer—between June 1 and Labor Day—TVA works to fill the reservoirs for recreational use. Additionally, reservoirs must be managed so that the riverbeds below their dams don’t dry out. 

So that all needs are met, TVA manages the system as a whole, and raises or lowers water levels accordingly.

How well the system is balanced is determined by measurements taken at Chickamauga Dam near Chattanooga, Tenn.—the location that provides the best indication of water flow in the upper Tennessee River system.

If the volume of water flowing into Chickamauga Reservoir is less than needed to meet systemwide flow requirements, additional water must be released from upstream reservoirs—even during summer months. Depending on the time period and water volume, 10 tributary reservoirs are considered for water release to improve overall system flow, resulting in a slight drawdown. These are: Blue Ridge, Chatuge, Cherokee, Douglas, Fontana, Nottely, Hiwassee, Norris, South Holston and Watauga.

 

Operating Guides

Based on the amount of water stored in these reservoirs in relation to the Minimum Operations Guide shown on the graph above, TVA will release enough water to meet the average minimum flows at Chickamauga Dam.

When dry conditions prevail on the Tennessee River below Chickamauga Dam, it may be necessary to release additional water to meet requirements at Kentucky Dam at the end of the system.

Water may also be released from reservoirs during summer months after significant storm events to ensure adequate flood storage capacity.

System Flow Requirements (June 1 – Labor Day)

  Weekly average minimum flow at Chickamauga Dam (cubic feet per second)
  June 1 - July 31 Aug. 1 - Labor Day
If the volume of water stored in tributary reservoirs is BELOW the Minimum Operations Guide 13,000 CFS 25,000 CFS
If the volume of water stored in tributary reservoirs is ABOVE the Minimum Operations Guide Increases from 14,000 CFS the first week of June to 25,000 CFS the last week in July 29,000 CFS

 

  Biweekly average minimum flow at
Kentucky Dam (cubic feet per second)
  June 1 - July 31 Aug. 1 - Labor Day
Kentucky flow requirement can drive minimum flows when conditions are dry below Chickamauga Dam. 18,000 CFS*
at Kentucky Dam
18,000 CFS*
at Kentucky Dam

*May increase up to 25,000 CFS for navigation.

You can see for yourself whether TVA is releasing water from upstream reservoirs. Check the endpoint for the Actual Storage Line on the Tributary System Operating Guide Graph above to see whether it is above or below the Minimum Operations Guide for today’s date. Then refer to the chart below to see the weekly average flow through Chickamauga Dam and compare it with the System Flow Requirements, shown above.

Reservoir Information

Get the most up-to-date information on the individual reservoirs TVA manages, including observed and predicted elevations, planned generation releases at the dams, reservoir operating guides, ecological health ratings, fish population survey results, recreation facilities and more.

 

 

Lake Info App

Want your lake info to go? Download the TVA Lake Info app, an easy-to-use resource for operating on and around reservoirs and dams in the TVA region. Available for iPhone and Android devices.